The concept multi-layer discs is practiced by many other media labs, but Hitachi claims that its quad-layer technology would be compatible with existing Blu-ray Disc drives after a firmware update. Prior developments of greater than dual layer discs have required special hardware to read the new media.

yup blockbuster has chosen Blu-Ray, Target has also expanded its Blu-ray shelf space, also considering HD-DVD's theoretical limit is quad layer 60GB, blu seems like the only choice just like it was whenit launched, especially since 200GB prototype discs are still being tested for compatibility. Blu-ray is also leading in sales everywhere, Oz,Uk,Us,Japan, i don't know why someone would choose an inferior technology such as HD-DVD.